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<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>

<body>
  <script>
    let num = 666
    let food = '柠檬'
    let dog = {
      type: '柯基',
      food: '骨头',
      color: '橘黄'
    }
    const dog2 = dog
    dog.color = '绿色'
    dog2.color = '粉色'
    console.log(dog)

    function sayHi () {
      console.log('你好~')
    }
    sayHi()
    for (let a in dog) {
      console.log(a)

    }
  </script>
</body>

</html>